Download circulatory system

Transport in
Humans
The circulatory system
Specification (2.49-2.59)
2.49 understand why simple, unicellular organisms can rely on diffusion
for movement of substances in and out of the cell
2.50 understand the need for a transport system in multicellular
organisms
2.57 describe the composition of the blood: red blood cells, white blood
cells, platelets and plasma
2.58 understand the role of plasma in the transport of carbon dioxide,
digested food, urea, hormones and heat energy
2.59 explain how adaptations of red blood cells, including shape,
structure and the presence of haemoglobin, make them suitable for
the transport of oxygen
Specification (2.60-2.62)
2.60 describe how the immune system responds to disease using
white blood cells, illustrated by phagocytes ingesting
pathogens and lymphocytes releasing antibodies specific to
the pathogen
2.61 understand that vaccination results in the manufacture of
memory cells, which enable future antibody production to
the pathogen to occur sooner, faster and in greater quantity
2.62 understand that platelets are involved in blood clotting,
which prevents blood loss and the entry of micro-organisms
Specification (2.63-2.66)
2.63
describe the structure of the heart and how it
functions
2.64
explain how the heart rate changes during exercise
and under the influence of adrenaline
2.65
describe the structure of arteries, veins and
capillaries and understand their roles
2.66
understand the general structure of the circulation
system to include the blood vessels to and from the
heart, the lungs, the liver and the kidneys
Small organisms just use diffusion
2.49
Explain why unicellular organisms can rely on diffusion for movement of substances in and out of the cell
The smaller the organism, the greater the SA: Vol ratio, meaning
diffusion of nutrients, waste and gases in and out is FAST
Large organisms need systems
2.50
Explain why unicellular organisms can rely on diffusion for movement of substances in and out of the cell
Large organisms:
• Smaller the SA: Vol ratio
• Bigger distance
Making diffusion of nutrients,
waste and gases in and out
SLOW
Systems for exchange (breathing and digestive) provide SURFACE AREA
The circulatory system deals with the problem of DISTANCE - diffusion just
has to work for the last fraction of a millimeter.
Plasma, red & white cells, platelets
2.57
Describe the composition of the blood: red blood cells, white blood cells, platelets and plasma
The role of plasma
2.58 understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy
The liquid part of the blood
Contains the cells and the protein that are essential
components of the blood
Carries substances to the tissues:
digested food, hormones
Removes waste from tissues:
carbon dioxide, urea
...and carries heat energy
Structure & function of red blood cells
2.59 describe the adaptations of red blood cells for the transport of oxygen, including shape, structure and the presence of haemoglobin
A small biconcave disc: the flat
shape provides a large surface
area and short distance to
maximize the rate of diffusion
without a nucleus so there is
maximum space for…
flexible so it can squeeze
through the capillaries.
…haemoglobin, a molecule
specially designed to hold
oxygen and carry it to cells that
need it.
Blood: defending against pathogens
2.60 describe how the immune system responds to disease using white blood cells, illustrated by phagocytes
ingesting pathogens and lymphocytes releasing antibodies specific to the pathogen
the two main types of white cells are
lymphocytes and phagocytes.
lymphocytes fight disease by making
antibodies to destroy pathogens by
making them stick together
Phagocytes engulf and digest pathogens
using enzymes.
Vaccination
2.61 understand that vaccination results in the manufacture of memory cells, which enables future antibody production to the pathogen to occur sooner, faster and in greater quantity
When a lymphocyte recognizes an antigen, it
multiplies and leaves some memory cells
One
lymphocyte
recognizes
the pathogen
lymphocyte
multiplies to
fight the
infection
Some of
these
lymphocytes
remain as
memory cells
How and why your blood clots
2.62 recall that platelets are involved in blood clotting, which prevents blood loss and the entry of microorganisms
1. Platelets are fragments of
cells, broken off larger cells.
2. When blood vessel
walls are damaged,
platelets produce
chemicals that convert
fibrinogen into fibrin
3. Fibrin forms a net that
traps other blood cells to
form a blood clot.
4. The clot
prevents blood
loss and the entry
of pathogens into
the body
The heart 1
2.63 describe the structure of the heart and how it functions
Pulmonary artery
Vena Cava from Body
Right Atrium
tricuspid valve
Aorta to Head and Body
Pulmonary vein
Left Atrium
semilunar valves
bicuspid valve
Right Ventricle
Left Ventricle
The heart 2
2.63 describe the structure of the heart and how it functions
blood from
the body
blood
from the
lungs
The ventricles contract,
putting pressure on the
blood. This closes the
tricuspid and bicuspid
valves and forces the
semilunar valves open.
Blood is forced into the aorta
and pulmonary artery
blood is forced through the
tricuspid and bicuspid valves
into the ventricles
Exercise, adrenaline and the heart
2.64 understand that the heart rate changes during exercise and under the influence of adrenaline
The cardiovascular centre in the
medulla controls the heart rate
by sending signals to the SA
node that make the heart
speed up or slow down.
During exercise, CO2 levels rise,
and the medulla speeds up the
heart rate, which increases the
amount of blood going to the
lungs.
When you have a shock,
adrenaline is released into the
blood. Adrenaline increases the
heart rate.
Arteries, veins and capillaries
2.65 describe the structure of arteries,veins and capillaries and understand their roles
Circulation to and from the organs
2.66 recall the general plan of the circulation system to include the blood vessels to and from the heart, the lungs, the liver and the kidneys
pulmonary artery
pulmonary vein
lungs
head & arms
aorta
vena cava
Right
hepatic vein
Left
liver
hepatic artery
hepatic portal vein
digestive system
renal vein
renal artery
kidneys
legs